Process of producing a textured sewing thread and a textured sewing thread made thereby



Oct. 27, 1964 G. R. ECKHARD 5 PROCESS OF PRODUCING A TEXTURED I THREAD AND A TEXTURED SEWING THREAD MADE REBY F'led 5 pt 1, 1960 INVENTOR. 6.2040491? fiffiJ/d I Y M QLQ 2797'TZ2NE v United States Patent 3,153,895 PROCESS OF PRODUCING A TEXTURED SEWING THREAD AND A TEXTURED SEWING THREAD MADE THEREBY George R. Eckhardt, Fords-Edison Township, Middlesex County, NJ., assignor to Coats & Clark, Inn, New York, N.Y., a corporation of Delaware Filed Sept. 1, 1960, Ser. No. 53,564 6 Claims. (Cl. 57-140) The present invention relates to textured sewing threads made of plied yarns (strands) and to the method of manufacturing the same.

A sewing thread made from plied yarns (strands) of synthetic filaments, because of the smoothness and uniformity of the filaments and of the thread resulting therefrom, has certain disadvantages well known in the art, as for example, the ease with which the yarns can be separated, and the tendency of the thread to slip in a stem. To reduce the tendency of the thread to slip in a seam, it has been proposed to produce a textured thread by fiutiing out the yarns from which the thread is made.

In a known method of producing a textured synthetic sewing thread, singles yarns (strands) from which the thread is made, are individually twisted and then are individually textured, in the manner described in United States Patent No. 2,783,609, to produce in the individual filaments of the yarns, coils, loops or whorls at random intervals along their lengths. The bulk of the yarn having its filaments so textured is increased. To texture the yarn individually as described, it is desirable not to twist the yarn to the full normal extent before texturing, but to twist the yarn to a low value, for example, from .05 to 14 t.p.i. (turns per inch of length) in order to facilitate the texturing process. Therefore, after the yarn with the low twist has been textured, additional twist is inserted in the yarn, so that the total twist is that normally used for the yarn. Two or more singles yarns, each individually twisted in one direction in two stages with an intervening texturing stage as described, are then combined and twisted in a reverse direction, to produce a balanced thread.

The known process described is not an economical one, since it requires a texturing device for each singles yarn (strand) and requires two separate non-successive stages of twisting before plying the yarns into a sewing thread. Moreover, with this process, physical differences are created between the yarns in each plied thread. These yarn diiferences can be further aggravated if uneven tensions are applied to the textured yarns during ply twisting. Further, inasmuch as the coils, loops or whorls produced in the individual filaments of each yarn are randomly distributed around the circumference of the yarn, such coils, loops or whorls tend to create a physical separation between yarns in the plied thread.

One object of the present invention is to provide a sewing thread, which has properties affording improved sewing and seaming performances, and which permits the use of economical techniques in its manufacture.

Another object of the present invention is to provide a process which produces the improved sewing threads described and which results in manufacturing economies.

In accordance with the present invention, the singles yarns (strands) of continuous synthetic filaments, made for example, from thermoplastic materials, such as polyamides of the nylon type, polyethylene terephthalate (Dacron), polyolefins such as polyethylene arid polypropylene, cellulose acetate, viscose rayon or other form of regenerated cellulose, polyacrylonitrile and the like, are individually twisted in one direction to the total twist normally used for the yarn. Two or more of these singles yarns, so fully twisted in the same direction are 3,1535% Patented Oct. 27, 1064- "ice combined and twisted in the same or reverse direction to form a unitary plied balanced thread structure. The singling and finishing twists can vary considerably for the same yarn and ply, and can vary according to the materials from which the filaments are made. Threads made from coarser deniers require less twist to maintain the same helix angle. The reverse is, of course, true for threads made from finer deniers. In any case, the selection of the proper twist is one within the ken of those skilled in the art having knowledge of the present invention, since it may correspond to the total twist in the singles yarns normally employed before plying, either in conventional processes where no texturing step is employed or in known processes where a texturing step is employed. The final or residual twist of the singles yarn in the plied thread should, in any case, be low enough, so that the filaments are not too tightly bound together, to permit eifective fluffing for texturing and should range from 0 to 20 turns per inch of length.

The finishing ply twist in the thread described being in the reverse direction to the singles yarn (strand) twist, this finishing ply twist removes at least some of the yarn twist, the number of singling yarn twists removed being approximately equal to the number of finishing twists inserted in the thread. The individual yarns will, therefore, end up in the twisted plied thread with a comparatively low twist, ranging from about 0 to 20 turns per inch of length, as described. With such low yarn twist in the plied thread, the filaments will not be twoo tightly bound in the thread and will be easily reoriented by the texturing step.

It is also conceivable that if yarns with low twists are used, the ply twist could be in the same direction as the yarn twist, as long as the yarns end up in the plied thread with comparatively low twist ranging about 0 to 20 turns per inch of length. The texturing process is a significant factor in balancing these threads.

The plied thread would have a finishing twist sufiicient to bind the yarns together and this twist would vary according to the size of the thread, the coarser thread requiring less twist. For example, for a heavy nylon 18 ply thread of about 4000 denier, the finishing twist may be lower than 5 turns per inch. For the finer threads, the finishing twist for practical purposes could be higher than 35 turns per inch of length.

The plied and twisted thread formed as described and having its singles yarns with a degree of twist, is textured to find out the singles yarns therein to increase their bulk and also to reorient the filaments such that the filaments of each yarn or ply of the plied thread pass and penetrate into the adjacent ply or plies of the thread, so that resistance to separation of the yarns of the plied thread is increased. The texturing step can be carried out by jetting a stream of air or other compressible fluid rapidly from a confined space to form a turbulent region. The plied twisted thread to be textured is fed into the fluid stream so that the filaments are reoriented and whipped in the turbulent region. As the thread is withdrawn from the region of turbulence, the filaments therein are so oriented as to form coils, loops or whorls, some of which pass into the adjacent yarn or yarns, thereby interlocking the yarns of the plied thread. The thread so treated and formed is then advanced to a take-up device.

The plied thread may be textured in the manner described in United States Patents No. 2,783,609 and No. 2,852,906 to produce in the individual filaments of the singles yarns in said thread, coils, loops or whorls at random intervals along their length. The feed device and the take-up device are regulated to impart overfeed (difierence in speed between thread feed and take-up) to the plied thread undergoing the texturing step.

I The finishing twist in the plied thread serves to stabilize the texture produced in the thread against any pull tending to straighten out the filaments and thereby to remove the texture. If desired, the loop texture imparted to the thread may be made even more stabilized by setting, as for example, with heat or steam, this stabilizing process being carried out either as a separate step mainly for stabilizing purposes, or as part of a dyeing or scouring process in which hot dyeing or scouring liquid is employed.

The process of the present invention reduces the number of texturing units required, reduces the costs of handling the materials and reduces the air requirement per pound of thread thereby effecting economies in relation to the known process in which the singles yarns (strands) are twisted individually in two stages with an intervening texturing stage before plying.

Moreover, the textured thread obtained by the process of the present invention produces a thread superior to that made by the known process. For example, in the known process, the texturing step applied to the singles yarns before plying can create physical differences between the yarns, as previously described. These yarn difierences are further aggravated if uneven tensions are applied to the textured yarns during ply twisting. When texturing follows the ply twisting operation as in the present application, the differences between yarns which may result from texturing and subsequent plying of the yarns can be eliminated. This is accomplished because the twisted thread is overfed during the texturing process, and any difference in effective length of any of the yarns in the plied structure due to unequal tension during ply twisting, is compensated for by a change in the looping characteristics of each of the singles yarns in the twisted thread during texturing. Because of this compensating effect, the resulting thread tends to have better balance and more uniform sewability and seam characteristics.

By forcing compressed air or other suitable gas through a plied twisted thread rather than through the singles yarns individually, the texturing loops produced in the filaments of each of the yarns of the twisted thread and the reorientation of the filaments in each of the yarns, tend to intertangle the yarns in the plied structure, thus locking the individual singles yarns together into a coherent unit, producing thereby a substantially homogeneous structure instead of the known plied thread in which the component yarns are readily separable. This intertangling of the singles yarns by the texture loops creates a cohesive force which opposes the tendency for the individual yarns in the thread to separate and the plied thread to untwist during sewing. By preventing the singles yarns in the thread from separating, the tendency for the thread to break due to snagging of one of the yarns by the hook or bobbin case during the sewing operation is greatly reduced. This interlocking of the yarns in the thread and the resulting resistance to ply separation, also improves the needle threading characteristics of the thread, as ply separation often creates difficulty in needle threading operation.

Also, because of the loops formed by texturing, a synthetic continuous filament thread is produced having a fibrous surface which materially reduces relative slippage of the thread and the seam into which it is sewn.

The method of the present invention also has the advantages of improving the threads resistance to permanent elongation, of improving stability of the thread (resistance to loop removal) when a longitudinal stress is applied, and of reducing a tendency to untwist during hand and machine sewing.

In the accompanying drawings there is illustrated one way in which the method of the present invention may be carried out in connection with a specific example. In the drawings,

FIG. 1 is a diagrammatic view of an apparatus for texturing the plied twisted thread in accordance with an embodiment of the present invention;

FIG. 2 is a schematic section through a texturing air jet device which may be employed for texturing the plied twisted thread in accordance with an embodiment of the present invention;

FIG. 3 is a perspective of a three-ply twisted thread shown on an enlarged scale prior to being textured in accordance with the present invention; and

FIG. 4 is a perspective of the plied three-ply twisted thread of FIG. 3 afiter being textured.

Referring to the drawings, each of the singles yarns 10, consisting of a plurality of continuous filaments of synthetic plastic material, is twisted in one direction with a number of turns which may correspond to the number of turns to which singles yarns are usually twisted before plying in conventional sewing threads, where the texturing process is not employed. Two or more of these singles yarns are then combined and twisted together in an opposite direction to produce a plied twisted thread 11, as shown in FIG. 3. The finishing twist will take out a number of turns of the singling twist in the yarn corresponding approximately to the number of turns in the finishing twist, so that the residual twist in each of the singles yarns will be approximately the difference between the singling twist and the finishing twist. This will reduce the residual twist in the singles yarns to a comparatively low figure, which makes the yarns ideally suited for texturing.

The plied twisted thread 11 shown in FIG. 3 is then taken oif a supply roll 12 (FIG. 1) which may take the form of a twister bobbin, passed through feed rolls 13 and then advanced through an air jet nozzle 15 (FIGS. 1 and 2) where the thread is textured to produce a textured thread 11a, shown in FIG. 4. The textured thread 11a is drawn by take-up rolls 17 and then advanced to a wind-up device to form a package 13. The feed device 13 and the take-up device 17 are regulated to impart overfeed (the difference in speed between thread feed and take-up) to the applied thread 11 undergoing the texturing step.

The air jet nozzle 15, per se, is of known construction and comprises a fitting 20 having a passageway 21 provided with an inlet 22 connected to a source of compressed air or other suitable gas under pressure and leading into the mouth of a venturi tube 23. Connected into the side of the fitting 20 is a plug 24 along which extends a hollow needle 25 reaching into the mouth of the venturi tube 23 and having an outlet 26 near said mouth. The thread 11 to be textured passes through the hollow of the needle 25 from its inlet end 27 and passes out of the outlet 26 of said needle and into the funnelshaped passageway of the venturi tube 23. The jet of compressed air admitted into the fitting 20 blows through the thread 11 passing through the venturi tube 23 and also creates turbulence in the venturi tube and near the outlet thereof which whips the filaments causing them to be reoriented and convoluted. The thread, as it is discharged from the venturi tube 23, is offset abruptly, so that the filaments which have been more or less reoriented in the region of turbulence, will be swirled into convolutions as the thread is withdrawn from this region. The thread withdrawn from the region of turbulence will be reformed with its filaments contorted into loops, coils and whorls arranged at random intervals along the length of the thread, as shown in FIG. 4. The thread so formed will have the advantages described above.

In a specific example for carrying out the process of the present invention, a denier yarn composed of 34 nylon filaments, is twisted with 22 right-hand turns per inch. Three of these yarns are combined and twisted together to impart l8 left-hand turns per inch to the plied thread. The thread so formed is then textured as de scribed.

In the specific example indicated, the air pressure s,153,sa

admitted into the air jet device would be about 98 pounds per square inch, the feed speed would be about 258 feet per minute, and the overr'eed would be about 5.2%. overfeed would be varied depending on the type of loop desired, the seam locldng characteristics recuired, and the particular sewability characteristics sought.

As indicated above, for practical purposes, the residual twist in the singles yarns of the plied textured thread of the present invention may vary between 0 and 20 turns per inch and the fmishing twist may range up to 40 turns per inch. Examples of difierent combinations of single twist and finishing twist which may be employed for nylon thread are indicated below.

The same singling and finishing twists may be employed for Dacron as is noted in the above examples for nylon. Usually, however, the Dacron twists would be higher than the nylon twists, as the specific gravity of the Dacron is 1.38 as compared to 1.14 for nylon. Dacron threads from the same denier, therefore, have smaller diameters than the nylon threads and require more twist to end up with the same twist helix angle.

While the invention has been described with particular reference to one embodiment, it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted by the scope of the appended claims.

What is claimed is:

1. A method of producing a sewing thread which comprises twisting two or more singles yarns of substantially the same number of continuous synthetic filaments having the same denier individually to the same number of twists in the same direction, combining the twisted yarns and twisting the combined yarns together to produce a substantially balanced plied thread structure, the difference between the singling twist and the finishing twist being such that the yarns in the plied twisted thread will have a twist of O to 20 turns per inch of length, and texturing the plied thread structure by the agitating action of a gas stream to produce loops at random in the filaments of the plied thread structure, the pressure, velocity of the gas stream and overfeed being sufficiently great to cause at least some of the loops formed in each yarn to penetrate into an adjacent yarn to interlock the yarns of the thread.

2. The method as d direction of twist in the singles yarns. method of producing a sewing thread which g two or more single yarns of substantial- .mber of filaments and denier individually ough the s number of twists per inch in the same direction, cor mg the individually twisted yarns, twist ing the combined yarns together to produce a plied thread structure, and t stirring the plied thread structure by produc ig loops in the filaments of the plied thread structure under conditions to cause at least some loops of each yarn to penetrate an adjacent yarn to lock the yarns together and form a balanced thread structure.

4. A balanced sewing thread comprising a plurality of individually twisted singles yarns each having substantially the same number of filaments, denier and twist per inch in the same direction, twisted and plied together, the filaments in each yarn being formed at random with loops, some of which pass and penetrate into the adjacent yarn to cause said yarns to be interlocked by the penetrating loops.

5. The method of producing a sewing thread having machine sewability, which comprises twisting two or more single yarns of substantially the same number of filaments and denier, and substantially the same physical characteristics individually through the same number of twists per unit of length in the same direction, combining the individually twisted yarns, twisting the combined yarns together to produce a plied thread structure, and texturing the plied thread structure by producing loops in the individual filaments of the plied thread structure under conditions to cause at least some of the loops of each yarn to penetrate an adjacent yarn to lock the yarns together, the number of twists applied individually to the single yarns and to the combined yarns, and the relative directions of said twists are such, as to produce a sewing thread having sufiicient twist balance to impart machine sewability to the thread.

6. A sewing thread having machine sewability, and comprising a plurality of individually twisted singles yarns substantially of the same number of filaments, denier and twist per unit of length in the same direction and having substantially the same physical characteristics, twisted and plied together, the filaments in each yarn being formed at random with loops, some of which pass and penetrate into the adjacent yarn to cause said yarns to be interlocked by the penetrating loops, the number of individual twists and of the combined twists, and their relative directions being such, as to produce twist balance in the thread.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,455 Camp Oct. 4, 1949 2,852,906 Breen Sept. 23, 1958 2,869,967 Breen Jan. 20, 1959 2,874,444 Griset Feb. 24, 1959 2,895,285 Hilbert July 21, 1959 2,911,784 Vandervoort Nov. 10, 1959 2,942,402 Palm June 28, 1960 3,020,699 Nijkamp et al Feb. 13, 1962 3,034,279 Gentle et al May 15, 1962 3,041,816 Stuewer July 3, 1962 FOREIGN PATENTS 558,177 Belgium June 29, 1957 824,729 Great Britain Dec. 2, 1959 

1. A METHOD OF PRODUCING A SEWING THREAD WHICH COMPRISES TWISTING TWO OR MORE SINGLES YARNS OF SUBSTANTIALLY THE SAME NUMBER OF CONTINUOUS SYNTHETIC FILAMENTS HAVING THE SAME DENIER INDIVIDUALLY TO THE SAME NUMBER OF TWISTS IN THE SAME DIRECTION, COMBINING THE TWISTED YARNS AND TWISTING THE COMBINED YARNS TOGETHER TO PRODUCE A SUBSTANTIALLY BALANCED PLIED THREAD STRUCTURE, THE DIFFERENCE BETWEEN THE SINGLING TWIST AND THE FINISHING TWIST BEING SUCH THAT THE YARNS IN THE PLIED TWISTED THREAD WILL HAVE A TWIST OF 0 TO 20 TURNS PER INCH OF LENGTH, AND TEXTURING THE PLIED THREAD STRUCTURE BY THE AGITATING ACTION OF A GAS STREAM TO PRODUCE LOOPS AT RANDOM IN THE FILAMENTS OF THE PLIED THREAD STRUCTURE, THE PRESSURE, VELOCITY OF THE GAS STREAM AND OVERFEED BEING SUFFICIENTLY GREAT TO CAUSE AT LEAST SOME OF THE LOOPS FORMED IN EACH YARN TO PENETRATE INTO AN ADJACENT YARN TO INTERLOCK THE YARNS OF THE THREAD. 